TY - JOUR T1 - Role of bronchus morphology on mucus mobilization during chest physiotherapy JF - European Respiratory Journal JO - Eur Respir J DO - 10.1183/13993003.congress-2015.PA4204 VL - 46 IS - suppl 59 SP - PA4204 AU - Benjamin Mauroy AU - Christian Fausser AU - Dominique Pelca AU - Jacques Merckx AU - Patrice Flaud Y1 - 2015/09/01 UR - http://erj.ersjournals.com/content/46/suppl_59/PA4204.abstract N2 - Based on pressures on the chest, chest physiotherapy (CP) is efficient but empirical, its mechanisms remain unknown. Historically, CP consists in applying strong pressures onto the chest. New techniques based on low pressures applied at small lung volumes have emerged, but still, they remain controversial. CP now needs scientific basis and we developed in the past years an integrated model of CP based on simplified physics and particularly on cylindrical airways (Mauroy B. et al, Phys Biol 2011; 8(5):056006; Mauroy B. et al, preprint arXiv, 2015).In order to improve this model and to understand how mucus motion is affected by the shape of the lumen area of the airways, we developed a numerical model of the biophysics involved in: 1/ the folding mechanism of the (small) airway walls that leads to "star-shaped" airways sections; 2/ the fluid mechanics of air and mucus in such complex cross-sectional geometries.Our results indicates that the star-shaped cross-section of an airway might reduce its inner mucus mobilization. As an example, in an airway with 1.5mm diameter suffering a constriction of about 30% its diameter, our model used with a circular section predicts that 50% of mucus is affected by air flow, while this quantity drops to less than 18% with a star-shaped section.This work shows that mucus standing in the folds can only be mobilized if air flow is kept at high levels. Moreover, the folds being deeper at lower lung volumes, our model suggests that a minimal lung volume may exist to be able to mobilize mucus in airways of a specific size. This behavior has been included in our integrative model of CP, and our results suggest this phenomenon might affect the global efficiency of low volume CP. ER -